title: New, clinically more relevant model for nerve root injury in the rat.
abstract: METHODS
  Exposure to nucleus pulposus and displacement of intraspinal nervous structures with assessment of spontaneous behavioral changes in rats.
  
  
  OBJECTIVE
  To develop a controlled, experimental model for nerve root injury.
  
  
  BACKGROUND
  There are a number of experimental models presented for studies on radiculopathies. One frequently used model is based on exposure to nucleus pulposus and displacement of the dorsal root ganglion (DRG). However, it is clinically more common that the nerve roots are displaced/compressed than the DRG. In this study, we developed a model for displacement of the nerve root by modifying the DRG model.
  
  
  METHODS
  After removing the left L3-L4 facet joint, the underlying disc was punctured, and the L4 nerve root was displaced laterally by an injection needle (n = 10). In sham experiments, the same procedure was performed without disc puncture and displacement (n = 10). In 10 rats, the left L4-L5 facet joint was removed. The underlying disc was punctured and the L4 DRG was displaced medially by an injection needle. Assessment of spontaneous behavioral changes was performed on days 1, 3, 7, 14, and 21, postsurgery.
  
  
  RESULTS
  There was a clear increase in duration of the behavior "unloading of the paw" after displacement of the DRG that was most pronounced on day 1 and then gradually declined. There was a similar pattern for this behavior induced by nerve root displacement, although the duration was higher than that for the DRG displacement. No apparent trends in behavioral changes were observed for the other behaviors studied.
  
  
  CONCLUSIONS
  Displacement of the nerve root induced more changes in the pain behavior than displacement of the DRG, but only for the behavior unloading of the paw. Because nerve root injury is more common than DRG injury, this model may be more clinically relevant than the DRG model.
  
  
  METHODS
  N/A.
authors.affiliation: *Musculoskeletal Research, Department of Medical Chemistry and Cell Biology, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden; and †Department of Orthopaedic Surgery, Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima, Japan.
authors.forename: Oscar
authors.initials: O
authors.lastname: Finskas
authors.forename: Asa
authors.initials: A
authors.lastname: Blixt
authors.forename: Yuki
authors.initials: Y
authors.lastname: Fujioka
authors.forename: Kjell
authors.initials: K
authors.lastname: Olmarker
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D005260:Female; D005727:Ganglia, Spinal / Q000503:physiopathology*; D006120:Grooming / Q000502:physiology; D007403:Intervertebral Disc / Q000294:innervation / Q000503:physiopathology / Q000601:surgery; D007405:Intervertebral Disc Displacement / Q000503:physiopathology; D008124:Locomotion / Q000502:physiology; D008159:Lumbar Vertebrae / Q000503:physiopathology / Q000601:surgery; D009068:Movement / Q000502:physiology; D011843:Radiculopathy / Q000473:pathology / Q000503:physiopathology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013126:Spinal Nerve Roots / Q000293:injuries / Q000503:physiopathology*; D021801:Zygapophyseal Joint / Q000503:physiopathology / Q000601:surgery